Keyboard or other similar apparatus for converting mechanical movement to a binary electrical signal using permanent magnet inhibited cores

ABSTRACT

The specification and claims disclose a keyboard for encoding information in a binary form in which a planar array of ferromagnetic cores are normally inhibited from switching by permanent magnets. One of the magnets is raised each time a key is struck and the cores adjacent this magnet are thereby uninhibited and produce an output indicative of the struck key.

United States Patent Charles B. Pear, Jr.

Centerport, N.Y.

Mar. 25, 1968 Apr. 6, 1 971 Potter Instruments Company, Inc. Plainview, N.Y.

Inventor Appl. No. Filed Patented Assignee KEYBOARD OR OTHER SIMILAR APPARATUS FOR CONVERTING MECHANICAL MOVEMENT TO A BINARY ELECTRICAL SIGNAL USING PERMANENT MAGNET INHIBITED CORES 4 Claims, 6 Drawing Figs.

U.S. Cl 340/365, 178/17, 340/174 Int. Cl ..G08c 19/28,

Field of Search 340/365,

345 (CK), 166 (C), 166 (C3), 174 (Digest); 178/17 (A), 17 (C), (Inquired) [56] References Cited UNITED STATES PATENTS 2,814,031 11/1957 Davis..... 340/174PM 2,997,703 8/1961 Powell... 340/365 3,058,097 10/1962 Poland 340/166C3 3,140,403 7/1964 Morwald 340/166C 3,439,117 4/1969 Mathemel 340/365 Primary Examiner-Thomas B. Habecker Att0rney-Laurence J. Marhoefer ABSTRACT: The specification and claims disclose a keyboard for encoding information in a binary form in which a planar array of ferromagnetic cores are normally inhibited from switching by permanent magnets. One of the magnets is raised each time a key is struck and the cores adjacent this magnet are thereby uninhibited and produce an output indicative of the struck key.

KEYBOARD OR OTHER SIMILAR APPARATUS FOR CONVERTING MECHANICAL MOVEMENT TO A BINARY ELECTRICAL SIGNAL USING PERMANENT MAGNET INHIBITED CORES BACKGROUND OF THE INVENTION This invention relates to an apparatus for converting mechanical movement to a binary electrical signal and, more particularly, to an improved keyboard encoder that is simple and economical to manufacture, is relatively maintenance free, is operable in adverse environments, and can serve as an input for electronic data processing machines.

The manually operated keyboard is one of the most common input devices for electronic data processing and other computing systems. These keyboards generate a coded electrical signal which is indicative of the key struck. Although there are a large number of different designs for such keyboards known in theprior art, none has proved entirely satisfactory from the standpoint of cost of manufacture, reliability of operation, and ability to function under extremes of ambient conditions.

One object of .this'invention is to provide a keyboard encoder which is not only easy and inexpensive to manufacture but is also simple and reliable in operation.

Another object of this invention is to provide such a keyboard which employs noncontacting electrical switching elements.

A further object of this invention is the provision of a keyboard-type encoder which has a minimum number of different components.

Briefly, this invention contemplates an encoder in which discrete electromagnetic coupling elements are arranged in a code pattern and movable magnets are so disposed with respect to the elements that they effect their coupling characteristics. Advantageously, the magnets are of uniform dimension, and infonnation is stored by means of the pattern in which the elements are arranged. The coupling elements contemplated by this invention are those that can couple a signal from an energizing or interrogating line to an output line, such as square-hysteresis-loop, ferromagnetic cores, for example. The actuation of a key or other mechanical actuation displaces one of the magnets from a certain group of elements so that these elements produce an output signal indicative of the magnet which has moved, and, hence, the key which has been struck.

An important adjunct of the invention is the provision for generating, in a simple, economical manner, either of two (or more) selectable outputs when a single key is struck, e.g., upper and lowercase characters. Since the elements that may be employed in the practice of this invention may be quite small, the elements for encoding one character may be arranged in one column and the elements for encoding another character may be arranged inan adjacent column that is so close that a single magnet covers the elements of both columns. With ferromagnetic cores, for example, one interrogating line may thread the cores of one column and another interrogating line threads the cores of the other column. A socalled shift key connects one or the other of the interrogating lines to a current pulse source and thereby determines which of two characters is encoded when a key is struck.

DESCRIPTION OF THE DRAWINGS Having briefly described this invention, it will be described in greater detail along with other objects and advantages in the following detailed description of a preferred embodiment which may be best understood by reference in the accompanying drawings. These drawin'gs form part of the instant specification and are to be read in conjunction therewith. Like reference numerals are used to indicate like parts in the various views;

FIG. 1 is a schematic view of two ferromagnetic cores and two magnets shown in respective .different positions with respect to the cores;

FIG. 2 is a perspective view showing two keys, which are typical of all the encoder keys, and their arrangement with respect to a core matrix;

FIG. 3 is an enlarged perspective view showing details of one of the keys of FIG. 2 and the cores associated with it;

FIG. 4 is an enlarged end view showing three keys of the encoder of FIG. 2;

FIG. 5 is an end view of a preferred embodiment of the invention showing key operated magnets that each cover two columns of cores;

FIG. 6 is a schematic view of a core matrix for a preferred embodiment of an encoder of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, two square-hysteresis-loop, ferromagnetic cores l2 and 12' are threaded by a common interrogating signal line 16 and signal output lines 18 and 18' respectively. The lines 16 and 18 pass through the center of the core 12 at approximately right angles to one another. These lines 16 and 18 also each make an angle of about 45 with respect to the plane of the core 12. Lines 16 and 18 are similarly disposed with respect to core 12' and all the lines (16, 18, and 18 are substantially coplanar.

As those skilled in the art appreciate, when a relatively strong permanent magnet 10 is disposed adjacent a small square-hysteresisloop, ferromagnetic core 12 the magnet biases the core in a flux pattern which is indicated by the arrows in the core 12. A core thusly biased is unable to switch to either a clockwise or a counterclockwise flux pattern; therefore, no flux change occurs in the core 12 when a current pulse (indicated schematically at 14) of either polarity is applied to an interrogating line 16. If the flux in the core does not change, there is no appreciable signal coupled to the output line 18.

With the magnet 10 displaced from the core 12', pulses 14 of alternate polarity cause the core to be magnetized alternately in a clockwise and counterclockwise direction. As the core 12 switches from magnetization in one direction to another, a signal is induced in line 18. This signal is indicated in an idealized fashion at 22.

Referring now to FIG. 2, in the keyboard encoder of this invention, a planar array of the ferromagnetic cores 12 are arranged in a code matrix. The magnets 10 are affixed at one end of key operated levers 24. Keys 32 are pivotally connected at the other end of the levers 24 and are arranged in rows and columns to form a keyboard as in common practice in the art. A rod 26 serves to pivot the levers associated with keys on the lowest row of the keyboard and a rod 28 pivots keys in the next row. Openings 34 in the levers 24 allow the pivot rods for one row of keys to pass freely through those levers for the keys of another row. In this manner, the ratio of the distances from the key 32 to magnets 10 are maintained equal for all rows. An additional rod would be provided for each additional row of keys on the keyboard.

' Referring now to FIGS. 3 and 4, in addition to FIG. 2, the magnet 10 may be a small strip of so-called magnetic rubber about l/ 16 inch wide and A inch thick. Such a piece of rubber can be magnetized so that it satisfactorily biases commercially available ferrite cores 12 when the magnet is within about 20 mils of the core. Magnetic rubber is a rubberlike composition heavily impregnated with barium or strontium ferrite powder usually oriented so that it is best magnetized along its thinnest dimension. Such material is commercially available from the B.F. Goodrich Corporation and from the Leyman Corporation of Cincinnati, Ohio.

Other magnetic materials or even electromagnets could be used in place of the magnetic rubber strips 10. A magnetic filed on the order of I00 oersteds removes practically completely the coupling effectiveness of the core.

FIG. 6 shows a portion of a typical code matrix array with the hammers removed for clarity. The cores 12 of this array are arranged, as viewed in FIG. 6, in vertical columns and horizontal rows.

Advantageously, at least some of the columns are disposed so closely together in pairs so that a single magnet 10, as shown by the phantom lines of FIG. 6, is disposed over the cores in the two adjacent paired columns. A more detailed view of this arrangement is shown in FIG. 5. This arrangement, in combination with a shift key, permits a single key to encode two separate characters such as upper and lower case characters, for example.

There is a column of cores for each character which the keyboard is to encode, and there are as many rows of cores as there are binary bits in code chosen. For the commonly employed eight bit EBCDIC code, for example, there are eight rows of cores.

An interrogation line 16 threads a first group of cores 12 and another interrogation line 16' threads a second group of cores 12 which are in the columns paired with the columns of the first group. With a shift key 40 in one position, the line 16 is connected to a high frequency pulse generator 42 via a differentiating transformer 41 which produces positive and negative output pulses of sufficient magnitude to switch the cores. Preferably, the pulse repetition rate of the generator 42 is quite high relative to the responsive time of a keyboard operator. A repetition rate of approximately 20,000 pulses per second is satisfactory. With the shift key 40 in its other position the line 16 is connected to the pulse generator 42. In effect, therefore, there are two coplanar arrays of cores 12; one array is energized with the shift key in one position while the other array is energized with the shift key in its other position. Since the cores of both arrays are coplanar and since the cores are quite small, one set of key operated magnets can serve both arrays, providing a simple, inexpensive dual mode operation for the keyboard.

An output line 18 threads each of the cores 12 that lie along a single row irrespective of whether the cores are in the first or second array. Thusly, when a key is struck, it raises the magnet covering a particular column, and an output pulse appears on those lines 18 that pass through a core in the uninhibited column in response to each pulse on line 16 (or 16). No output appears on those lines 18 where there is no core since the other inhibitedcores along the line 18 neither produce an output themselves nor effect the output from an uninhibited core. Similarly, uninhibited cores an adjacent paired column (if any) do not appreciably effect the output on lines 18 owing to the fact that these cores are not energized.

Advantageously, one row of the matrix (the bottom row of FIG. 6) has a core in every column so that there is an output on the line 18 that threads this row irrespective of which key is depressed. This output may serve to generate timing pulses. For certain codes, the output cores in this row may comprise part of the code. For other codes, the output of these cores may be independent of the code. The line 18 threading the bottom row is coupled to a three input coincidence or AND gate 58, the output of which triggers a one-shot multivibrator 59.

It should be noted that the cores in the array of FIG. 6 are so oriented that the outputs cancel from adjacent cores threaded by a single interrogating line (16 or 16'). Noise signals generated by the cores along a line 18, therefore, tend to cancel. However, in that row in which there is a core in every column (the bottom row of FIG. 6) adjacent cores are advantageously oriented so that their outputs add as is also shown in FIG. 6. This arrangement provides an indication of the event when two keys are struck simultaneously since, in this event, the output on this line 18 will be approximately twice the output from the switching of a single core. The line 18 which threads the bottom row of cores 12 is coupled to a suitable amplitude detector 5 I known in the art, which produces an output when the amplitude of the signal on line 18 exceeds substantially the signal produced by a switching of a single core. This output is coupled via an inverter 55 to another input terminal AND gate 58 so that AND gate 58 is disenabled when the amplitude of the signal on line 18 exceeds a certain amount. The third input to AND gate 58 is coupled to pulse generator 42. In operation, AND gate 58 produces an output for triggering one-shot 59 each time a single key is struck but does not produce an output if two keys are struck simultaneously.

The output of one-shot 59 is coupled to another one-shot 62 whose output is in turn coupled as an enabling input to each of the AND gates 56. The pulse duration of the output pulse of one-shot 59 is conveniently equal in duration to the duration of about five pulses from generator 42. This provides a slight delay that prevents spurious signals from being passed by the AND gates 56. Similarly, the duration of the output pulse of one-shot 62 is also equal to about five pulses from generator 42 in order to insure that there will be an output pulse on each one 18 where there is an uninhibited core irrespective of the state of that core when the magnet 10 is removed.

The outputs of AND gate 56 are coupled to a storage register 66 where the information corresponding to the key struck may be stored temporarily as is the common practice in the art. In order to reset the register 64 after the magnet 10 is returned to its rest position, the lowermost line 18 that threads a core in each column is coupled via an interrogator 65 and an inverter 67 to one input of an AND gate 69. The other input of AND gate 69 is coupled to the output stage of register 64 whose input is coupled to the lowermost row of cores.

The output of AND gate 69 triggers a reset pulse generator 66. As will be appreciated by those skilled in the art, with this arrangement, pulse generator 66 is triggered to reset the register when simultaneously the lowermost stage of the register 64 is set and there are no pulses on the lowermost line 18. This situation occurs after the magnet 10 has been returned to its rest position.

In operation, with the shift key 40 contacting the line 16, for example, a series of positive and negative pulses from pulse generator 42 continuously interrogate the cores l2 that are threaded by the line 16. With the key operated magnets 10 disposed closely adjacent these cores, they are so biased so that no output appears on line 18. When one of the keys is depressed, it raises one of the magnets 10, and the cores in that column are uninhibited. The pulses on line 16 thereafter cause a flux reversal in the cores in the uninhibited column, and output pulses are coupled to each line 18 where there is a core in the uninhibited column. It should be noted that owing to the relatively high pulse repetition rate, a number of pulses may appear on line 16 during the time the magnet 10 is raised. This insures that the core will switch.

It will be understood that with the shift key coupled to line 16, the output on lines 18 is determined by the presence or absence of a core in the uninhibited column which is threaded by the line 16 rather than line 16.

As previously explained, the first positive output pulse on the line 18 threading the bottom row of cores may be used for timing purposes. Thusly, following an initial delay equal to the duration of about five pulse periods, if a pulse thereafter appears on one of the lines 18 within another period also equal to about five pulse periods this pulse is stored in the register 64. In this manner the information corresponding to a struck key is stored.

Thus, it will be appreciated that the objects of the invention have been accomplished. The keyboard is not only easy and inexpensive to manufacture, it is also simple and reliable in its operation. Particularly, it should be noted that there is no need for mechanical contacts in this novel encoder. In addition, since the information is encoded in the presence or absence of a core, all the keys can be substantially identical in manufacture, thus, reducing the number of different components.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims. It is further obvious that various changes may be made in details within the scope of the claims without departing from the spirit of the invention. For example, other discrete coupling elements, such as Hall effect generators, permanent magnet twister memory elements,

deposited film memory elements, and the like, may be used in place of ferromagnetic cores, if desired. It is, therefore, to be understood that this invention is not to be limited to the specific details shown and described.

lclaim: I

1. An apparatus for convening a mechanical movement to a binary electrical signal, comprising in combination:

an array of discrete electromagnetic coupling elements arranged in groups;

means coupled to said elements for energizing said elements;

means coupled to said elements for providing an output from said elements;

said elements respectively coupling said energizing means with said outputmeans;

information being stored as the presence or absence of certain ones of said elements in said groups of elements;

a plurality of movable means for effecting the coupling of said elements of respective ones of said groups of elements, each of said movable means movable between a first position in which said individually movable means has a first effect on the coupling by the elements of said group, and a second position in which said individually movable means has a second different effect on the coupling by the elements of said group;

at least one additional group of said coupling elements;

means for energizing said additional group of coupling elements selectively and independently of the means for energizing the elements of said array; and

said additional group of coupling elements being so disposed so at least one of said movable means in its first position is disposed to effect both the coupling of the elements of said additional group and the coupling of at least one group of said coupling elements of said array.

2. An apparatus for converting mechanical movement to a binary electrical signal as in claim 1 wherein said groups are aligned in columns and the elements of said columns are aligned in rows and at least one of said rows has an element in each of said columns.

'3. An apparatus for converting mechanical movement to a binary electrical signal as in claim 2 wherein the cores in adjacent columns in said row in which there is a core in each column are oriented so that their outputs add.

4. An apparatus for converting mechanical movement to a binary electrical signal as in claim 3 wherein said permanent magnets are made of magnetic rubber and further including manually operated keys for moving said movable means. 

1. An apparatus for converting a mechanical movement to a binary electrical signal, comprising in combination: an array of discrete electromagnetic coupling elements arranged in groups; means coupled to said elements for energizing said elements; means coupled to said elements for providing an output from said elements; said elements respectively coupling said energizing means with said output means; information being stored as the presence or absence of certain ones of said elements in said groups of elements; a plurality of movable means for effecting the coupling of said elements of respective ones of said groups of elements, each of said movable means movable between a first position in which said individually movable means has a first effect on the coupling by the elements of said group, and a second position in which said individually movable means has a second different effect on the coupling by the elements of said group; at least one additional group of said coupling elements; means for energizing said additional group of coupling elements selectively and independently of the means for energizing the elements of said array; and said additional group of coupling elements being so disposed so at least one of said movable means in its first position is disposed to effect both the coupling of the elements of said additional group and the coupling of at least one group of said coupling elements of said array.
 2. An apparatus for converting mechanical movement to a binary electrical signal as in claim 1 wherein said groups are aligned in columns and the elements of said columns are aligned in rows and at least one of said rows has an element in each of said columns.
 3. An apparatus for converting mechanical movement to a binary electrical signal as in claim 2 wherein the cores in adjacent columns in said row in which there is a core in each column are oriented so that their outputs add.
 4. An apparatus for converting mechanical movement to a binary electrical signal as in claim 3 wherein said permanent magnets are made of magnetic rubber and further including manually operated keys for moving said movable means. 